Sponge, algae, what?

[christa1421]

I received this Ricordea Yuma mushroom that came on a rock but it has this black stuff on it. I did a dip with coral rx before I put it in the tank. The mushroom opens up and covers it during the daytime, but at night, when the mushroom shrinks down I can see it. Not sure if this is black sponge, or a type of algae, or fungal infection? Should I try to remove it? I did gently go over with a toothbrush…doesn’t come off. So if it is a sponge hopefully I didn’t hurt it if it’s good.

 

[KrisReef]

I’m thinking it is a mushroom with sponge on the rock that it came with. If it’s not moving around then I think you’re okay with it.